JPH0368404B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an unmanned guided vehicle, and more particularly to a control method for an unmanned guided vehicle that expands the control range and improves control accuracy.

As is well known, unmanned guided vehicles that transport cargo in factories, warehouses, etc. are designed to travel while detecting magnetic lines of force emitted by guide wires buried or affixed to the travel path. That is, based on the error signal obtained from a detection means (guide sensor) such as a coil attached to the unmanned guided vehicle, the deviation from the guide wire and the direction of deviation are detected, and the deviation is adjusted to zero. The vehicle runs under automatic control.
This error signal is indicated by the symbol V _E in Fig. 1A, and takes a positive or negative value depending on whether the deviation direction is to the right or left of the guiding line l, and is zero when the deviation is zero. This is a signal whose absolute value increases as the deviation increases, and the unmanned guided vehicle automatically travels so that this error signal _VE becomes zero.

In this kind of driving control, the unmanned guided vehicle runs without deviating from the aisle guidance line l, but it may run due to changes in the condition of the driving road surface, such as due to the material of the floor surface (floor tiles, concrete, etc.) or the adhesion of water, oil, etc. There have been cases where the vehicle deviated from the guide line 1 due to fluctuations in resistance and further due to bending of the guide line 1 at the turning section. When such an inconvenience (off-route) occurs, the unmanned guided vehicle automatically stops, and the system administrator has to manually perform the recovery work.

By the way, the above-mentioned off-route detection is performed based on the reference signal _VN shown in FIG. 1B. This reference signal V _N is a signal that is maximum when the unmanned guided vehicle is directly above the guide line l, that is, when the deviation is zero, and decreases as the deviation increases. This is what is output from.
Then, when the reference signal V _N becomes less than a predetermined value,
It is determined that the unmanned guide has deviated from the guide line l by a predetermined distance or more, and off-route detection is performed. According to this, even when the guide wire 1 is disconnected and the reference signal V _N becomes zero, it can be automatically stopped, and a fail-safe configuration can be achieved.

By the way, in the conventional unmanned guided vehicle mentioned above, in order to improve the function of returning the unmanned guided vehicle to just above the guide line l (hereinafter referred to as the centering function),
When trying to increase the amplitude of the error signal V _E ,
There was a problem that the amplifier became saturated when the deviation was small, making it impossible to perform proper feedback control. For example, in Figure 1A, the deviation d=d ₁
The amplitude of the error signal V _E takes the maximum value a ₁ when , but if this maximum value a ₁ is made to match the maximum amplitude of the amplifier, the above-mentioned problem will not occur.
However, if the amplification factor is further increased, for example, the deviation d=
At the time d ₂ (<d ₁ ), the error signal V _E reaches the maximum amplitude of the amplifier, and even if the deviation d increases, the error signal V _E
A phenomenon occurs in which the amplitude of the signal does not increase, and correct feedback control becomes impossible.

In order to avoid such inconvenience, it is necessary to create a centering area (hereinafter referred to _as
(referred to as the first zone), for example - in Figure 1
Even if it is set between Z ₁ and _{Z 1} and sufficiently amplified, the error signal V _E
Centering control may be performed in a region where the amplitude of the unmanned guided vehicle does not exceed the maximum amplitude of the amplifier, and when the unmanned guided vehicle goes outside the first zone, it is immediately determined to be off-route and the vehicle is automatically stopped. However, according to such a method, since the first zone becomes narrow,
Even if an unmanned guided vehicle deviates for a short period of time at a turning point, etc., it will be judged as off-route and will automatically stop, and the system administrator will have to manually return to the vehicle each time, which is extremely complicated. It was hot.

Furthermore, as shown in Fig. 2, the conventional guide sensor has a reference coil CN disposed horizontally so as to be perpendicular to the guide line l, and an eccentric whose axis is placed obliquely on a virtual vertical plane containing the guide line l. and a position detection coil CE, and the reference signal V _N ,
Although an error signal V _E was generated, the deviation detection coil CE receives not only the induced starting force due to the deviation in the left and right direction, but also the induced starting force due to the angular deviation between the unmanned guide person and the guide line l. For example, even if the guide sensor is on the guide line l, the error signal V _E will not necessarily be zero unless the unmanned guided vehicle and the guide line l are parallel, that is, the angular deviation is zero. Therefore, there was a problem that accurate centering control could not be performed.

In view of the above circumstances, the present invention provides a control method for an unmanned guided vehicle that can perform stable and highly accurate automatic driving control by adding an automatic return function to the centering function. An unmanned guided vehicle detects an error signal regarding the amount of angular deviation, the direction of deviation, and the amount of deviation formed between the guide line and the guide line, and controls the unmanned guided vehicle to automatically travel based on the error signal. In the control method, a first detection means detects the amount of angular deviation of the unmanned guided vehicle with respect to the guide line, and a second detection means detects the direction and amount of deviation of the unmanned guided vehicle with respect to the guide line. Separately providing a detection means and a reference signal output means for outputting a reference signal that outputs a maximum value when the unmanned guided vehicle is on the guide line and whose output value decreases as the amount of deviation increases; , a first zone in which the unmanned guided vehicle performs centering control based on the output of the second detection means; and a first zone arranged outside the first zone, in which the output of the first detection means and the second detection are detected. a second zone in which the unmanned guided vehicle performs automatic return control in the direction of the guide line based on the output of the reference signal output means;
It is determined which zone the unmanned guided vehicle is in based on the output of the detection means, and when the unmanned guided vehicle is in the second zone, the unmanned guided vehicle is moved along the guide line based on the output of the first detection means. , the unmanned guided vehicle is guided along an arc having a predetermined radius of curvature based on the output of the second detection means, and automatically returns to the first zone. shall be.

Embodiments of the present invention will be described below based on the drawings.

FIG. 3 shows zones and position signals according to an embodiment of the present invention.
FIG. 3 is a conceptual diagram showing the relationship between Vp and reference signal _VN . In the figure, l is the guiding line, and both sides of it (−Z ₁ −
A _first zone N1 is provided (between -Z 2 and -Z 1 and between Z ₁ and Z 2), and a second zone ZN is provided outside it (between -Z ₂ and -Z 1 and between Z ₁ and _{Z 2} ).
2 is provided. Further, a third zone ZN3 is provided outside the second zone ZN2. Here, in the first zone ZN1, the unmanned guided vehicle is controlled to be centered in the direction of zero by the position signal Vp, and in the second zone ZN2, it is controlled by the angle signal V _A and the position signal Vp, which will be described later. Tight guide wire l
Automatic return control is performed in the direction of. Furthermore, if the unmanned guided vehicle deviates to the third zone ZN3, it will be judged as off-route and automatically stopped. In this case, the reference signal is used to determine which zone the unmanned guided vehicle is in.
This is done by V _N or position signal Vp. For example, when the reference signal V _N is V _N V ₁ , the first zone
ZN1, and when V ₂ < V _N < V ₁ , the second zone ZN2
Furthermore, when V _N <V ₂ , it is determined that the zone is in the third zone ZN3 (see FIG. 3B).

Here, the feature of this embodiment is that the first zone ZN1
The width _2Z1 is narrower than that of the conventional one, for example, the conventional width of about 30 mm has been set to about 10 mm.

Further, the position signal Vp has sufficient amplitude within the first zone ZN1, thereby enabling highly accurate centering control.

Next, FIG. 4 is a block diagram showing the configuration of the unmanned guided vehicle in the above embodiment. In the figure,
1 is a left wheel motor that rotationally drives the left wheel 1a, and 2 is a right wheel motor that rotationally drives the right wheel 2a, and these are designed to be rotationally driven separately. Further, 3 and 4 are rotation control circuits that control the rotation of each of the motors 1 and 2, and the rotation control circuit 3 on the left side has a difference V _L −Vp between the left wheel speed command V _L and the position signal Vp.
is supplied from the summing point 5, and the right rotation control circuit 4 receives the sum of the right wheel speed command V _R and the position signal Vp V _R +
Vp is supplied from summing point 6. The position signal Vp is output from the guide sensor 7 and is supplied to the summing point 5 and the inverter 10 via a switch 9 that is turned on/off by a control circuit 8.
The voltage is applied to the summing point 6 from the inverter 10. In addition, left and right wheel speed commands V _L and V _R
is supplied from the control circuit 8 to each summing point 5, 6. Furthermore, the position signal Vp, reference signal V _N and angle signal V _A output from the guide sensor 7 are as follows:
The signal is supplied to the control circuit 8 via an A/D (analog/digital) converter 11.

Here, as shown in FIG. 5, the guide sensor 7 includes a reference coil CN, an angle detection coil CA perpendicular to this and parallel to the guide line l, and a position detection coil CP perpendicular to both coils. and by these induced starting forces, the signal V _N and the angle signal
V _A , which generates a position signal Vp. In this case, the reference signal V _N is the same as the conventional one, but the position signal Vp is not superimposed with any induced electromotive force due to angular deviation, unlike the conventional error signal V _E , and the guide line l and the unmanned guided vehicle are The distance changes as shown in Figure 3A, depending on the distance between the two. Further, the angle signal V _A is a signal proportional to the sine sin θ of the angular deviation θ between the guide line l shown in FIG. 6 and the unmanned guided vehicle.

In such a configuration, the unmanned guided vehicle typically
The vehicle runs in the first zone ZN1 while controlling settering. That is, the control circuit 8 controls the reference signal V _N
When V ₁ (FIG. 3B), it is determined that the unmanned guided vehicle is in the first zone ZN1, the switch 9 is turned on, and automatic travel control is performed while appropriately controlling the left and right speed commands V _L and _VR . In this case, if the unmanned guided vehicle deviates to the right of guide line l, the position signal
Vp becomes positive, the right wheel motor 2 rotates at a speed of V _R +Vp, and the left wheel motor 1 rotates at a speed of V _R −Vp, guiding the unmanned guided vehicle to the left to perform centering control. Also,
When it shifts to the left, the position signal Vp becomes negative,
The left wheel motor 1 becomes faster than the right wheel motor 2 and directs the unmanned guided vehicle to the right. Thus, the first zone
While ZN1 is running, depending on the amplitude of the position signal Vp, the
Centering control is performed by changing the speeds of the right wheels 1a and 1b so that the vehicle always runs directly above the guide line 1.

Next, when the unmanned guided vehicle enters the second zone ZN2,
Automatic return control is performed to return this to the guide line l. That is, the reference signal V _N is V ₂ < V _N < V ₁
(FIG. 3B), the control circuit 8 determines that the unmanned guided vehicle has entered the second zone ZN2, turns off the switch 9, and performs the following control.

(1) Place the unmanned guided vehicle parallel to guide line l (see Figure 7). In this case, it is determined whether the deflection direction is to the right or left depending on the polarity of the position signal Vp, and if the deflection direction is to the right, the speed command V _L of the left wheel 1a is set to zero, and the speed command V _R of the right wheel 2a is set to zero. at low speeds (e.g. 0.5km/
h), and if the deflection direction is to the left, do the opposite. As a result, the unmanned guided vehicle has left wheel 1a.
(Right wheel 2a) moves in the direction of the first zone ZN1 while drawing an arc with the right wheel 2a as the turning center, moves from the position shown in Fig. 7 A to the position shown in B, and the unmanned guided vehicle is parallel to the guide line l (that is, at an angle deviation θ=0)
When the angle signal V _A becomes zero, the right wheel speed command V _R becomes zero.

(2) Bring the unmanned guided vehicle closer to guide line l (see Figure 8).

If the unmanned guided vehicle becomes parallel to the guide line l by the control in (1), then it will run in an arc as shown in FIG.
, that is, so that the position signal Vp becomes zero.

Now, assume that the unmanned guided vehicle is traveling on an arc centered on point P in Fig. 9, and the speed of the left wheel 1a is V _L ,
The speed of the right wheel 2a is V _R and the turning radius (i.e. point P
and the distance between the left wheel 1a and the left wheel 1a) is R, the pitch between the driving wheels (that is, the distance between the left wheel 1a and the right wheel 2a) is L _T , the distance between the guide sensor 7 and the driving wheel is L _S , the guide sensor 7
Let L be the distance measured along the guide line l, and let L be the distance between the guide sensor 7 and point P before and after the movement.
Letting L ₁ , L ₂ and the amount of deviation be d, the following relational expression can be obtained.

N _R /N _L =R+L _T /R ...(1) Here, since L ₁ = L ₂ , R
When we search for R=2L _S・L+d ² +L ² /2d−L _T /2...(4). In this equation, the distances L _T and L _S are constant, and the deviation d is found from the position signal Vp, so if the distance L is set to an appropriate value in advance, the turning radius R can be found from equation (4). By substituting this R into equation (1), the speed ratio of the left and right wheels can be determined.
In this way, for example, by setting the speed N _L of the left wheel 1a to an appropriate value, the speed N _R of the right wheel 2a is determined, and when the vehicle travels a distance L at this speed, the guide sensor 7 comes directly above the guide line l. At this time, the angular deviation θ occurs again, but in order to reduce this, it is sufficient to increase the distance L and make the vehicle travel with a large turning radius.
Then, when the guide sensor 7 comes on the guide line l,
The control device 8 turns on the switch 9 again and issues equal speed commands V _L and V _R to the left and right wheels 1a and 2a,
Centering control is performed in the same way as the centering control in the first zone ZN1. Thus, the second zone
In ZN2, the speed commands V _L and _VR are controlled based on the angle signal V _A and the position signal Vp, and automatic return control is performed.

It is the same as before that when the vehicle enters the third zone ZN3, it is deemed to be off-route and the vehicle is automatically stopped immediately.

As explained above, the present invention includes a first detection means for detecting the amount of angular deviation of the unmanned guided vehicle with respect to the guide line, and a first detection means that detects the direction and amount of deviation of the unmanned guided vehicle with respect to the guide line. A second detection means and a reference signal force means for outputting a reference signal that outputs a maximum value when the unmanned guided vehicle is on the guide line and whose output value decreases as the amount of deviation increases are separated. a first zone in which the unmanned guided vehicle performs centering control based on the output of the second detection means; and a second zone in which the unmanned guided vehicle performs automatic return control in the direction of the guide line based on the output of the second detection means, and based on the output of the reference signal output means or the output of the second detection means. determining which zone the unmanned guided vehicle is in, and when the unmanned guided vehicle is in the second zone, directing the unmanned guided vehicle in a direction parallel to the guide line based on the output of the first detection means. After that, the unmanned guided vehicle is guided along an arc having a predetermined radius of curvature based on the output of the second detection means and automatically returns to the first zone, so that the centering control and the automatic Return control can be performed more accurately.
Furthermore, since the range of automatic return can be widened, the frequency of manual return by the operator can be reduced.

[Brief explanation of drawings]

FIG. 1 is a conceptual diagram showing the relationship between the guide line l, error signal V _E , and reference signal V _N in a conventional unmanned guided vehicle.
FIG. 2 is a perspective view showing the configuration of the main parts of a conventional guide sensor, FIG. 3 is a conceptual diagram showing the relationship between each zone, position signal Vp, and reference signal _VN according to an embodiment of the present invention, and FIG. The figure is a block diagram showing the configuration of the control system of the unmanned guided vehicle according to the same embodiment, and FIG. 5 is a perspective view showing the configuration of the main part of the guide sensor 7 in the same embodiment.
Fig. 6 is a plan view for explaining the angular deviation θ, Figs. 7 and 8 are plan views for explaining the movement of the unmanned guided vehicle during automatic return control, and Fig. 9 is a plan view for explaining the movement of the unmanned guided vehicle during automatic return control. FIG. 2 is a diagram for explaining the turning radius R, etc. CA...Angle detection coil (first detection means),
CP...Position detection coil (second detection means), d...
...Amount of deviation, l...Guiding wire, V _A ...Angle signal (output of the first detection means), V _E ...Error signal, V _N ...
...Reference signal, Vp...Position signal (output of second detection means), ZN1...First zone, ZN2...Second
Zone, θ...Amount of angular deviation.

[Claims]

1 A non-contact obstacle detection sensor 5 is provided at the front of the vehicle body 1, and the obstacle detection sensor 5
A traveling vehicle is provided with a control device 12 that controls the traveling means or steering operation means of the vehicle body 1 based on the obstacle sensing results, [B] The obstacle sensing sensor 5 detects the position of the obstacle. A plurality of sensing areas are provided in the left and right directions of the vehicle body 1.
The vehicle body 1 is detected separately into A ₁ to _{A 3} .
It is composed of a plurality of non-contact obstacle sensors 5A and 5B arranged in parallel in the left-right direction. [B] The sensing areas _A1 to _A3 by the obstacle sensors 5A and 5B are areas that are sensed by each of the obstacle sensors 5A and 5B alone, and areas that are sensed by the adjacent obstacle sensors 5A and 5B at the same time. The sensing area is divided into multiple types of sensing areas. [C] The obstacle sensors 5A and 5B are set to repeatedly measure obstacles at predetermined time intervals _t0 . [d] The control device 12 controls the sensing areas A ₁ to
Based on changes in the presence or absence of obstacle detection in A ₃ .

Claims (1)

2 zone, the unmanned guided vehicle is directed in a direction parallel to the guide line based on the output of the first detection means, and then the unmanned guided vehicle is directed in a direction parallel to the guide line based on the output of the second detection means. A method for controlling an unmanned guided vehicle, comprising guiding the vehicle along an arc having a predetermined radius of curvature and automatically returning the vehicle to the first zone.